Most dogs enjoy chewing on things, although preferences vary as to the hardness of the substances favored. Some dogs like to chew on very hard materials such as cow bones, wood, nylon, others prefer softer chews such as polyurethane or rubber while still others favor freeze dried snacks. Some dogs, due to their age, may not be able to chew on the very hard substances. Young dogs have insufficiently developed teeth, while old dogs may have diseased gums or may have lost some of their teeth.
The growing trend in the area of animal chews has been directed toward the area of edible chews that are wholly digestible. Many such edible or digestible chews have been developed. Generally these chews are formed from “natural resins”. Examples of natural resins that may be used for animal chews may include casein, potato starch, vegetable starch, vegetable matter, or comminuted rawhide as a primary ingredient. Typically, such primary ingredient is combined with various attractants and/or flavorings to make the chew more desirable.
Edible/digestible animal chews have been manufactured by first combining the natural base ingredient, i.e., casein, potato starch, vegetable starch, vegetable matter, or comminuted rawhide, with desired attractants and/or flavorings. The combined ingredients may then be injection molded into a desired shape, such as a dog bone, etc. However, the molding operation of such resins has been found to be problematic.
Specifically, the natural ingredients tend to assume tacky or sticky surfaces as molded, and often may exhibit a great deal of adhesion to the mold cavity. This makes it very difficult to extract the molded chew from the mold without damaging the chew. The edible/digestible nature of the chew further complicates extraction by limiting the available mold release that may be advantageously used if such mold release is undesirably absorbed into the chew toy at an unacceptable level.
Additionally, at the time of demolding, animals chews molded from natural resins are typically very soft in character. This soft character in conjunction with the sticky nature further complicates the forming processes. Specifically, conventional ejector pins present a relatively small surface area that, in combination with the resistance to demolding, results in a large amount of pressure being applied to the soft chew at the region of the ejector pin. This large pressure often results in the ejector pin punching into, or even through the molded chew. Not only does this produce a cosmetic defect in the chew, but can also further complicate demolding, as the chew may now be skewered on an ejector pin. At the very least, the high localized pressure of the ejector pin may result in a cosmetic defect in the form of a circular indentation.
Accordingly, it is an object of the present invention to address the problems associates with the molding of natural resin based animal chews such that the chews may be more efficiently released from the mold without the problems associated with standard ejector pin design.